In Did You Know? the National Geographic magazine team shares extra information we gathered to expand your knowledge of our featured subjects.

Photography and art have a long history of assisting in conservation.

The world's first national park, Yellowstone, was established as a direct result of work by photographer William Henry Jackson and painter Thomas Moran. Both men traveled with the Hayden Survey to the Yellowstone region in the summer of 1871, the year before Yellowstone was proclaimed a park. Without their efforts, it might have taken much longer for the U.S. Congress to recognize the treasures of the area, which might have allowed competing needs to intervene. The government was interested in exploiting western resources to rebuild the nation after the Civil War, and the Northern Pacific Railway had recently been laid across what would become the state of Montana. Settlers were already heading west into the area.

Earlier reports of Yellowstone's unique characteristics—a deep yellow canyon, spouting holes, whistling vents, bubbling mud, rainbow-colored pools of simmering water—were hard for anyone to believe without seeing them in person. Reports from hunters, trappers, and explorers who had traveled through the area were ridiculed as tall tales, but they intrigued Ferdinand Hayden, director of the U.S. Geological Survey. He set out with a team that included Jackson and Moran to document the geography, resources, and sights of the region. Once Jackson brought back incontrovertible photographic proof of the physical characteristics of the area—the beauty and wonder of such a large section of the American West—and shared it with the government and the general public, it was hard to ignore the call to preserve this for future generations. Moran's large-scale paintings, in the days before color photography, brought the vivid colors to life.

The black-and-white photograph on the opening spread of our parks portfolio, "Hallowed Ground," in the October issue, was taken by William Henry Jackson on the surveying trip with Hayden in 1871. The person shown standing on the mineral terraces at Mammoth Hot Springs is painter Thomas Moran. Together, these two artists captured the magic of Yellowstone, and their amazing images convinced the U.S. Congress to protect the treasures of Yellowstone by creating the world's first national park.